When Autodesk announced their Spark 3D printing platform and subsequent SLA 3D printer, the Ember, it caught many within the industry, including us, off guard. What it did seemingly show, however, was that the company, known for their design software, was taking the 3D printing industry very seriously. That’s not all though, as at the time it appeared that they saw SLA technology as the future of the desktop 3D printing space. At least that’s what we thought…

This last week, a very interesting and innovative patent was published by Autodesk, detailing several methods of FDM/FFF 3D printing with multiple colors and multiple nozzles. Although we’ve seen numerous startups tease various methods of printing using a mixture of filament, the patent, which was filed in September of last year for a ‘Material Dispensing System,’ is remarkably comprehensive. Autodesk was sure to cover multiple methods, techniques, and inventions within a single patent.

First let’s start with the ability for an FDM/FFF machine to mix more than one filament, in this case as many as 7 different strands within a single hotend. You may be thinking to yourself that such a process would get incredibly expensive and possibly slow the movement of the machine down under all the weight, as 7 different motors would be required to feed each strand of material individually. Autodesk, however, has figured out multiple ways to overcome these issues. The first method would require the mounting of each motor on the frame of the printer and then the filament would be fed into a single hotend where it’s mixed. This approach would only solve the possible weight issues one would encounter, as multiple motors would still be required to move each strand of material. The second approach, which in my opinion is ingenious, is to use a single motor to drive all 7 strands of filament. They accomplish this by inventing a new apparatus, as seen to the right, which is able to use the printer’s natural motion to change the filament that’s being extruder, yet only a single motor is required to feed all 7 strands of filament to the hotend. They describe this process of changing which filament is selected to be driven, in the passage below which also refers to the diagram to the right:

“When selector arm 3016 is pushed laterally, it causes a ratchet arm 3020 to push and rotate selector ring 3032. When selector ring 3032 rotates, cam arm 3026 and roller 3042 move with it. Roller 3042 rolls off of the currently engaged bevel gear 3028, which then disengages from transfer gear 3046. Roller 3042 then rolls onto the next bevel gear 3028 causing it to be pushed radially inward and engage with transfer gear 3046, and therefore for its associated filament 3036 to be driven when motor 3006 rotates. When force is removed from selector arm 3016, it is sprung back into its nominal position by spring 3024. Ratchet arm 3020 also moves back and ratchets over sloped teeth 3034 as it does so. The selection motion can be repeated indefinitely in the same direction and no reversing motion is required to get to select any particular filament.”

With this method, there is also the ability to change nozzles to different sizes allowing the user to print thicker and thinner layers within a single print project, on the fly. To do this, the inventors detail a nozzle system, as pictured below, which extrudes the mixed filament (shown as 2006), or the single color filament in various sizes via the nozzles shown as (2016, 2018 and 2020). For instance, a user could be printing with a color mixture via nozzle (2006), and then require thicker infill material which does not need to be a specific color. They will then have the printer switch over to the larger nozzle (2016) and print the infill at a much quicker rate. Subsequently, there may be a requirement to print a very fine layer of a specific color within the same project, at which point the printer will switch to nozzle (2020). This system can be seen in the diagram below:

The inventors also depict several other methods to feed multiple strands of filament into a single hotend, all which could have applicable uses within different FDM machines. Below is just one of these methods, which actually does tether 6 motors onto a single hotend apparatus.

Yet another promising method they depict within this filing is the use of a stacked selectable multi-material drive system which feeds each strand of filament through conduits to independent dispensing nozzles. The description of this mechanism reads as follows:

“The selection of which filament is accomplished as the system drives a pushrod up against a selector arm. The sector arm moves other components to change which filament is being fed. The selector arm is only pushed in one direction and may be pushed any number of times to sequentially and cyclically index through all filaments.”

Although in their diagram (to the right) six different filaments are shown in use, the patent filing states that in theory any number of filaments could be used and selected to be driven by a single motor.

Clearly Autodesk has taken a substantial amount of time figuring out how to evolve current FDM technology in a way which will allow for much more detailed, intricate prints. If it wasn’t for the fact that these patents were filed only nine months ago, I would likely feel that they may have lost interest in this area. But the fact that the company was working on the Ember 3D Printer as they were filing these patents, indicates to me that they are still very serious about FDM/FFF technology.

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